Depends on the model. Some say you must use premium gas but still fun fine on 87. Others will knock and cough like the devil. Just put about 1/4 tank of 87 in and see how it runs. If it runs badly, just top it off with 93 and it should be okay.

Lower octane fuels don't do the damage. Detonation is the culprit. The engine is equipped with a knock sensor. It will adjust the timing to allow use of lower octane fuel. If you experience pinging under load just go light on the throttle. If you don't want to compromise performance then fill with premium gas.

I do not know how much, if any, alcohol they run in fuel in Texas, but I can tell you that 87 octane fuel , mixed for a winter blend in new england, plus ten percent alcohol we have to run, makes most knock sensor equipped trucks turn into slugs once the computer pulls all the timing out to prevent detonation.

Lower octane fuels don't do the damage. Detonation is the culprit. The engine is equipped with a knock sensor. It will adjust the timing to allow use of lower octane fuel. If you experience pinging under load just go light on the throttle. If you don't want to compromise performance then fill with premium gas.

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THIS IS 1000% corect !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I have run 2 tanks of Premium and the gas mileage did increase to 15.5 from the upper 12's. I don't know if this is due to the break in period so I can not say that it runs any different. At 2700 miles now.

Oddly enough I have a 90' Lumina eurosport with the 3.1 multiport, and it has the same sticker on the inside of the gas filler. We tried a tank of 87 in it one time, and the engine ran horrible. Erradic idle, misfired, and surged under load. Took it home and syphoned the gas out, and filled it back up with Premium 93 and it ran fie ever since.

I run premium in my 6.2L...I also did an "experiment" on my Yukon, I ran premium for a few tanks and ran regular for a few tanks doing the same type of driving and I got about 4.5 mpg better with premium. The cost pretty much worked out to be the same, better mileage for more initial cost compared to less mileage with less initial cost...plus the premium is that much better for your engine. I run premium all the time now.

Oddly enough I have a 90' Lumina eurosport with the 3.1 multiport, and it has the same sticker on the inside of the gas filler. We tried a tank of 87 in it one time, and the engine ran horrible. Erradic idle, misfired, and surged under load. Took it home and syphoned the gas out, and filled it back up with Premium 93 and it ran fie ever since.

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chances are that the computer in that is not as good as modern trucks, and that's why it ran so poorly